摘要
采用动态亚格子应力大涡模拟方法对射流式离心泵射流器进行研究,探讨瞬态静压情况对射流式离心泵初生空化特性的影响,并与SST k-ω湍流模型的模拟结果进行对比.结果表明:基于时间平均的SST k-ω湍流模型不能很好地模拟泵喉管内部的压力脉动情况,压力值随时间变化基本保持恒定值;基于动态亚格子模型的大涡模拟结果则能得到压力脉动随时间的变化,且得到的结果也更能反映实际情况,与试验结果相一致;高速流体与低速流体相互作用的剪切层位置处形成围绕喷嘴的圆环形柱状涡带,失稳涡带发生扭曲变形产生强烈的压力脉动,这种扭曲变形的涡带向下游发展并吸收高速流体的能量,使其分解的涡带导致脉动幅值在进入喉管处达到最大值,因此该处较容易发生空化.
Large eddy simulation with dynamic sub-grid stress model was adopted to study on fluid dynamics in the jet nozzle of a self-priming centrifugal pump to examine the effects of transient pressure fluctuation on incipient cavitation characteristics in the pump and the results were compared with those obtained by means of the SST k - to turbulence model. The results show that the time-averaged SSTk-ω model cannot adequately simulate the pressure pulsation features at the throat of the nozzle, sho- wing a constant value over time basically. However, the large eddy simulation with dynamic sub-grid stress model is able to get a variable pressure pulsation profile over time, and the profile agrees well with experimental results, reflecting the actual situation of pressure pulsation. A vortex ring is formed downstream the jet in the nozzle, which is generated in the shear layer between the the suetioned fluid with low velocity and the driving fluid of high velocity. The instable vortex induces a voilent pressure fluctuation. A twisted vortex ring propagates downstream and absorbs the kinetic enegy of the fluid with high velocity. The ring collapses at the throat to produce the largest pressure pulsation amplitude. As a result of this, cavitation is mostly prone to occur there.
出处
《排灌机械工程学报》
EI
CSCD
北大核心
2017年第5期369-374,共6页
Journal of Drainage and Irrigation Machinery Engineering
基金
国家自然科学基金资助项目(51509111)
江苏省普通高校研究生科研创新计划项目(KYLX15_1064)
江苏高校优势学科建设工程项目
关键词
射流式离心泵
射流器
压力分布
空化
大涡模拟
flow-ejecting centrifugal pump
jet aerator
pressure distribution
cavitation
large-eddy simulation
